Oil wells generally comprise a positive pressure pump located beneath the surface within the oil source. The pump is mechanically operated from the surface by a rod string operated by a walking beam apparatus. The rod string passes into the well at the surface of wellhead through a stuffing box, and the upper portion of the rod string is enclosed in a polished rod which provides a smooth surface to wear against the seals in the stuffing box. The reciprocating motion of the polished rod makes the oil flow up to the wellhead from where it is piped to storage. The stuffing box uses seals or packing to prevent leakage from passing out of the stuffing box from around the reciprocating rod. However, the harsh environment at the wellhead (corrosive chemicals, sand and abrasives, etc.) can cause the seals or packing in the stuffing box to deteriorate rapidly, thereby allowing oil to pass through the worn seals and be thrown about the immediate environment due to the reciprocating action of the rod. The Environmental Protection Agency has developed strict regulations against such occurrences and therefore it is important to provide sensors at the wellhead for recognizing stuffing box failure and for generating a signal to alert responsible operators to take appropriate action.
There are some existing apparatus to detect stuffing box leakage. Some methods surround the stuffing box by a reservoir of lubricant maintained at a static fluid pressure, which is substantially higher than the pressure at which the oil is produced from the well. A drop of the pressure in the reservoir indicates a leakage of the stuffing box. Some methods use container/salvage chamber to collect leaking oil. When the level of fluid in the container reaches a certain point, the leakage is detected. Existing methods require disruption of the oil well operation for their installation, and some even require modification to the stuffing box and/or wellhead piping and components. There is room for a new method and apparatus that is easy to install without interfering with wellhead operation.